This invention relates to loading dock lighting systems, of the type intended to shine light inside a tractor trailer, van, railroad car, etc., when present at a loading dock at a warehouse or other shipping or receiving location. Loading vehicles, such as fork lifts and pallet lifters, are used in bringing goods and materials into a trailer or out of a trailer when the same is stationed at a loading dock. In order to help provide enough light for the fork lift operator during loading or unloading, it is often necessary to use a dock light. These items typically project from some structure, such as the edges or vertical guides of the dock door or gate, or can sometimes be installed on a post or bollard at the loading dock gate. One example of this is discussed in U.S. Pat. No. 7,101,064. These dock lights project out from the doorway or from the side of the bollard into the lanes that are traversed by the fork lifts or other equipment, and thus they are subject to collision damage. The docking equipment industry is aware of this problem, but has been unable to address it.
Dock safety lights are typically employed at loading dock doors to signal to the fork lift operator, on the inside or proximal side of the dock door, whether the dock door is open or closed, and also to signal to the operator of a truck or tractor on the outside or distal side whether the dock door is closed or open. The standard convention is that when the dock door is closed, the inside safety light shines a red light and the outside safety light unit shines a green light, and when the dock door is open, the inside safety light shines green and the outside safety light shines red. These are mounted on a wall alongside the door on the interior and exterior, respectively, and let the fork lift operator know, with a green light, that the operator can proceed safely to load or unload the trailer or truck body, or with a red light that the door is closed and he should not proceed. When the dock door is open, the outside safety light signals with a red light that the truck operator should not drive away, and when the dock door is closed, signals with a green light that it is now safe to drive away from the loading dock.
Typically wall space is quite limited, especially on the inside of the shipping/receiving dock area, and there is also limited space for electrical wiring and cabling to the safety light units and to presence sensors that detect whether the dock door is open or closed. The inside safety light unit has to be mounted high on the wall, and it can be difficult for the fork lift operator to see the safety light if the operator is carrying a high or elevated load, which is typically the case during a loading operation.